Optical disc apparatus

Abstract

Before tracking control is turned on, there is determined a correction formula for correcting a balance value of a tracking error signal depending on a position of a movable lens for spherical aberration correction. Then, after the tracking control has been turned on, using an RF signal as an index, the adjustment of the position of the movable lens for spherical aberration correction is performed, while the balance value of the tracking error signal is corrected by use of the correction formula. An adjustment value for adjusting the balance value of the tracking error signal at a time point of completing the adjustment of the position of the movable lens for spherical aberration correction is stored.

Description

[0001]This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2011-127471 filed in Japan on Jun. 7, 2011, the entire contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an optical disc apparatus.[0004]2. Description of Related Art[0005]In a typical optical disc apparatus, upon start-up, adjustments are performed by following a procedure described below.[0006]First, using a tracking error signal as an index, a rough adjustment of spherical aberration correction is performed, followed by automatic gain control of the tracking error signal, and tracking control is pulled in. Moreover, after that, using an RF signal as an index, a fine adjustment of spherical aberration correction is performed, and a focus control loop gain and a tracking control loop gain are adjusted, after which the start-up is completed. This completion of the start-up enables...

AI Technical Summary

Benefits of technology

[0009]An object of the present invention is to provide an optical disc apparatus that is capable of preventing a tracking servo from becoming unlocked during and after an adjustment at start-up in which an RF signal is used as an index.

[0012]Moreover, the correction formula determination portion may detect values of the adjustment value for adjusting the balance value of the tracking error signal obtained when the movable lens for spherical aberration correction is at at least two different positions, respectively, at which the balance value of the tracking error signal becomes optimum, and determine the correction formula based on a result of the detection. Particularly in a case where the correction formula determination portion detects values of the adjustment value for adjusting the balance value of the tracking error signal obtained when the movable lens for spherical aberration correction is at two different positions, respectively, at which the balance value of the tracking error signal becomes optimum, and determines a linear approximate expression based on a result of the detection to use it as the correction formula, the time required for determining the correction formula can be reduced.

Problems solved by technology

In the fine adjustment of spherical aberration correction carried out after tracking control has been turned on, however, a balance value of a tracking error signal varies with a change in the position of a movable lens for spherical aberration correction disposed in an optical system of an optical pickup, and due to the variation in the balance value, a tracking servo may become unlocked, rendering the adjustment in progress unable to be continued.

None of these, however, discloses or suggests a technique for preventing, when spherical aberration correction is performed, a tracking servo from becoming unlocked due to a variation in the balance value of a tracking error signal.

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